JPS6233090A - Alloy powder for building up of powder - Google Patents

Abstract

PURPOSE:To improve the shape of weld beads and to prevent the generation of blowholes by specifying the oxygen and nitrogen contents of Ni-base alloy powder to be used for build-up welding of powder. CONSTITUTION:The Ni-base alloy powder for build-up welding of powder has a spherical shape of <=1.5 ratio between the major and minor axes and is adjusted to 0.01-0.50wt% oxygen content and <=0.30wt% nitrogen content. The excellent feeding property of the powder in the build-up welding stage is thus obtd. The welding to the good bead shape without generating the blowholes in the build-up metal is thus executed.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention is directed to powder overlay welding using powder overlay welding.
This relates to base alloy powder.

(Prior Art) In order to impart corrosion resistance, heat resistance, abrasion resistance, etc. to the surface of a substrate, or to further improve the above-mentioned characteristics of the surface of the substrate, surfacing Pa (Surfacing) is often performed.

Various types of overlay welding methods have been developed, but the powder overlay welding method, which uses powder as a filler material and a plasma arc as a heat source, includes the oxyacetylene welding method using a filler rod, TIG It has attracted particular attention in recent years because it is faster and easier to automate than welding methods.

The alloy powder used in this powder overlay welding can be prepared by: ■ Spraying the molten alloy with gas and then cooling it in gas; ■ Spraying the molten alloy with gas and then immersing it in liquid (water). A method of cooling, ■ A method of spraying liquid (water) onto the molten alloy, ■ A method of applying centrifugal force to the molten alloy,
■A method in which molten alloy flows down into the gap between rolls rotating at high speed.

Manufactured by etc.

In such a powder manufacturing method, when the cooling rate after the molten alloy is powdered by atomizing is slow, the molten powder becomes spherical due to the surface tension of the molten alloy, but when the cooling rate is high, the molten powder becomes spherical. It has previously solidified, resulting in an irregularly shaped powder.

(Problems to be Solved by the Invention) By the way, the irregularly shaped powder described above has a large length ratio and is not constant, so when this powder is used as a powder for powder overlay, In this case, the feedability of the powder is poor.

Therefore, in the past, various improvements have been made to the powder feeding mechanism, but even so, there are problems such as poor bead shape due to uneven powder feeding, for example, lack of hot water, uneven bead width of overlay metal, etc. There was a problem that defects were likely to occur.

On the other hand, the powder produced by the gas atomization method, which has a low cooling rate, has a spherical shape with a small length ratio, so the powder feedability is good, and the bead shape is also good.

However, although the bead shape is good, there is a problem in that blowholes may occur in the overlay metal.

This invention was made by focusing on the above-mentioned conventional problems, and because it has excellent powder feeding performance, problems such as running out of hot water and uneven bead width do not occur, and the bead shape is good. At the same time, it is possible to perform powder overlay welding without blowholes in the textured metal.
The purpose is to provide an o-based alloy powder.

[Structure of the Invention] (Means for Solving the Problems) The alloy powder for powder overlay welding according to the present invention is a Co-based alloy powder used for powder overlay welding, and more preferably has a length ratio of 1. It has a spherical shape of .5 or less and has an oxygen content of 0.0.
It is characterized in that the nitrogen content is 1 to 0.50% by weight and 0.30% by weight or less.

As mentioned above, the alloy powder for powder overlay according to the present invention has an oxygen content of 0.01% by weight or more, and the reason for this is that the blowholes in the overlay metal after powder overlay welding are minimized. This is to eliminate it. From the viewpoint of eliminating blowholes in the overlay metal, the amount of oxygen in the powder is 0.50.
It is sufficient if it is less than % by weight, more preferably 0.0
The range is 2 to 0.30% by weight. Also, the amount of nitrogen is 0.
By setting the content to 30% by weight or less, it becomes possible to reduce or eliminate the occurrence of blowholes in the overlay metal.

The Co-based alloy powder for powder overlay welding according to the present invention is used when performing powder overlay welding in order to improve the wear resistance, heat resistance, corrosion resistance, chemical resistance, etc. of the surface of a substrate. The preferred component range of C:
0.05-3.0%, Si: 5.0% or less, Mn: 3.
0% or less, P: 0.03% or less, S: 0.03% or less,
Cu: 3.0% or less, Ni: 30% or less, Cr: 10~
40%, W: 20% or less, Mo: 20% or less, B
: 3.0% or less, Fe: 5% or less, Nb: 3.0% or less, Ta: 3.0% or less, V: 3.0% or less, Zr: 3.
0% or less, N: 0.30% or less, O: 0. O2N2.5
0%, the balance being Co and impurities is more preferred.

In this composition, C is effective in forming carbides and increasing hardness and high-temperature strength, so it is more preferable to use zero carbon.
．． The content should be 0.5% or more, but if it is too large, the toughness and ductility will decrease, so it is more preferably 3.0% or less.
Since Si reduces non-metallic inclusions in the overlay metal, it is more desirable to add it in a range of 5.0% or less,
Since Mn increases the cleanliness of the overlay metal, it is more desirable to add it in a range of 3.0% or less, and since P and S impair the toughness of the overlay metal, it is more desirable to add both 0.03% or less. % or less. Also, since Cu improves strength, it may be added up to 3.0%, and Ni
Since Cr contributes to improving corrosion resistance, it may be added up to 30%.Furthermore, Cr improves corrosion resistance and wear resistance, so it is more desirable to add 10% or more, but if it is too large, the toughness will deteriorate. More preferably 4 because it has low r.
It is preferable to set it to 0% or less. Yet again.

W improves wear resistance, so it may be added up to 20%, Mo increases corrosion resistance and strength, so it may be added up to 20%, and B improves strength, so it can be added up to 20%.
You can add up to %.

Fe can reduce the cost of the powder without impairing the properties of the overlay metal, so it may be added up to 5% or less, and in order to improve the strength, Nb can be added up to 3.0% or less and Ta can be added. Up to 3.0%, ■ up to 3.0%, Z
r may be added up to 3.0% or less.

The alloy powder for powder overlay according to the present invention is preferably made of a Co-based alloy having the above-mentioned composition range,
More preferably, it has a spherical shape with a length ratio of 1.5 or less. Such a spherical powder is manufactured using a manufacturing method 1, usually a gas atomization method, which involves a cooling rate in which powdered molten metal becomes spherical due to its surface tension and then solidifies.

The alloy powder for powder overlay according to the present invention contains or adheres oxygen in the range of 0.01-0.50% in the Co-based alloy powder, and limits Nu to 0.30% or less. We tried to prevent blowholes from occurring in the overlay metal, but in order to achieve such an amount of oxygen, for example, ■ A method of adjusting the amount of oxygen in the molten metal when melting a Co-based alloy. , ■ A method of adjusting the amount of oxygen in the atomizing gas (adding oxygen to the atomizing gas as necessary), ■ A method of adjusting the amount of oxygen in the atomizing atmosphere.

■A method of heat treating powder to oxidize its surface.

(2) There are methods such as pickling the powder to oxidize its surface, and these methods can be used alone or in combination. In addition, the average oxygen content can be set to 0.01 to 0.50%.

(Example 1) After melting a Co-based alloy, the molten Co-based alloy was heated with N2
The powder was pulverized by a gas atomization method using gas, and cooled in a gas atmosphere in a chamber/liquid in which the amount of oxygen in N2 gas was adjusted to 300 to 11,000 pp to produce a Go-based alloy powder.

When we investigated the ingredients of each powder, we found that No. 1 in Table 1.
The results are shown in Figures 1 and 2.

For comparison, Co3 alloy powder was produced by pulverizing Co-base alloy molten metal by a gas atomization method using N2 gas and cooling it as it was in a N2 gas atmosphere without adding oxygen, and without oxygen addition treatment. A powder was prepared. The components of this powder are shown in No. 003 in Table 1.

Furthermore, for comparison, a molten Co-based alloy was pulverized by a gas atomization method using N2 gas and then poured into water. The components of this powder are shown in No. 014 in Table 1.
Sphericity (long/short ratio) of each powder with the composition shown in 1 to 4,
When we investigated fluidized dust (JIS method), the results were also shown in Table 1.
Powder No. 4 has an irregular shape, has a large length ratio, and has poor flowability.

Subsequently, using the powder shown in Table 1, powder overlay welding was performed on the substrate surface under the conditions shown in Table 2. The particle size of the powder used was -60 to +350 meSh.

Table 2 Next, when we examined the average number of blowholes in 100 valves in the overlay weld metal using X-rays, we found that
The results are shown in the table.

Furthermore, when the appearance defect rate of overlay weld metal was investigated for 100 valves, the results were the same (as shown in Table 1). In the case of Nos. 1 and 2, there is almost no occurrence of blow holes in the overlay weld metal because it contains an appropriate amount of oxygen, and there is also a high level of fluidized powder dust, which prevents hot water from running out and bead width defects. It was possible to obtain a good weld bead shape with no problems such as uniformity and no appearance defects.

On the other hand, when feel welding was performed using No. 3 powder with a low oxygen content, there were many blowholes in the overlay weld metal, and No. 3 powder had an irregular shape with a large length ratio. When overlay welding is performed using powder 4,
The undesirable result was that the weld bead shape was not good and the appearance defect rate was high.

(Example 2) After melting a Co-based alloy, the molten Co-based alloy was heated with N2
The powder was pulverized by a gas atomization method using gas, and then cooled in a gas atmosphere to produce a Co-based alloy powder.

Next, the powder was heated at 600°C for 1 hour (
Oxidation was carried out by heating for 5 hours (No. 5 (7) case) and 5 hours (No. 6 + 7 case). When the components of each powder were examined, the results were shown in Nos. 5 and 6 in Table 3.

For comparison, Co-based alloy powder was produced by pulverizing Co-based alloy molten metal by a gas atomization method using N2 gas and cooling it as it was in an N2 gas atmosphere without adding oxygen, and without oxygen treatment. A powder was prepared. The components of this powder are shown in No. 7 in Table 3.

Next, the sphericity (long/short ratio) and fluidized dust (JIS method) of each powder having the composition shown in Nos. 5 to 7 in Table 3 were examined, and the results were also shown in Table 3.

Subsequently, using the powder shown in Table 3, powder overlay welding was performed on the substrate surface under the conditions shown in Table 4. Note that the particle size of the powder used was -60 to +350 mesh.

Table 4 Next, the average number of blowholes in 100 valves in the overlay weld metal is x! ! When investigated by a,
The results are shown in Table 3.

Furthermore, when the appearance defect rate of overlay weld metal was investigated for 100 valves, the results were also shown in Table 3.

As shown in Table 3, in the cases of Nos. 5 and 6 using the alloy powder for powder overlay according to the present invention, blowholes in the overlay weld metal hardly occur because they contain an appropriate amount of oxygen. In addition, because the powder has a high fluidity, there were no problems such as running out of hot water or uneven bead width, and a good weld bead shape with no appearance defects could be obtained.

On the other hand, when overlay welding was performed using N017 powder with a small amount of oxygen, an unfavorable result was obtained in that there were many blowholes in the overlay weld metal.

[Effects of invention

Claims (7)

[Claims] (1) The Co-based alloy powder used for powder overlay welding has a spherical shape, an oxygen content of 0.01 to 0.50% by weight, and a nitrogen content of 0.30% by weight or less. Characteristics of Co-based alloy powder for powder overlay. (2) The amount of oxygen in the Co-based alloy powder is 0.02 to 0.30
The Co-based alloy powder for powder overlay according to claim (1), which is % by weight. (3) The composition of the Co-based alloy powder is C: 0.05 in weight%
~3.0%, Si: 5.0% or less, Mn: 3.0% or less, P: 0.03% or less, S: 0.03% or less, Cu: 3
．． 0% or less, Ni: 30% or less, Cr: 10-40%,
W: 20% or less, Mo: 20% or less, B: 3.0% or less, Fe: 5% or less, N: 0.30% or less, O: 0.01
Co-based alloy powder for powder overlay welding according to claim 1 or 2, comprising ~0.50% Co and the balance Co and impurities. (4) Nb: 3.0% or less, Ta: 3.0% or less in Co.
Co for powder overlay according to claim (3) containing 0% or less, V: 3.0% or less, Zr: 3.0% or less
Base alloy powder. (5) The Co-based alloy powder for powder overlay according to any one of claims (1) to (4), wherein the spherical alloy powder has a length ratio of 1.5 or less. (6) The alloy powder containing oxygen is the powder according to any one of claims (1) to (5), in which oxygen is added by adjusting the amount of oxygen in the atomized gas. Co-based alloy powder for overlay. (7) For powder overlay according to any one of claims (1) to (6), the alloy powder containing oxygen is one to which oxygen has been added by heat treatment and oxidation. Co-based alloy powder.